/// <summary>
/// When given an asteroid, calculate the number of asteroids visible (ie not occluded) from this object.
/// Then update the "AsteroidsVisible" property on the input object with that count.
/// </summary>
/// <param name="targetAsteroid"></param>
internal void UpdateAsteroidsInFOV(Asteroid targetAsteroid)
{
HashSet <double> angles = new HashSet <double>();
foreach (var asteroid in Asteroids)
{
if (asteroid == targetAsteroid)
{
continue;
}
double slope = targetAsteroid.GetAngle(asteroid);
angles.Add(slope);
}
targetAsteroid.AsteroidsVisible = angles.Count;
}
/// <summary>
/// A helper function that generates a SortedDictionary containing all valid angles between the source object
/// and any neighbour Asteroids. Each angle in the SortedDictionary contains a SortedList sorted on the distance
/// between the source and neighrbour object.
/// Distance is actualy the square of the distance to avoid the expensive sqrt operation.
/// </summary>
/// <param name="sourceAsteroid"></param>
private SortedDictionary <double, SortedList <double, Asteroid> > GetDictionaryOfNeighbours(Asteroid sourceAsteroid)
{
SortedDictionary <double, SortedList <double, Asteroid> > anglesWithNeighbors = new SortedDictionary <double, SortedList <double, Asteroid> >();
foreach (Asteroid asteroid in this.Asteroids)
{
if (asteroid == sourceAsteroid)
{
continue;
}
double angle = sourceAsteroid.GetAngle(asteroid);
if (anglesWithNeighbors.ContainsKey(angle) == false)
{
anglesWithNeighbors.Add(angle, new SortedList <double, Asteroid>());
}
double distance = Math.Pow(sourceAsteroid.X - asteroid.X, 2) + Math.Pow(sourceAsteroid.Y - asteroid.Y, 2);
anglesWithNeighbors[angle].Add(distance, asteroid);
}
return(anglesWithNeighbors);
}